“However, the site is also located on Metropolitan Open Land, which is protected from inappropriate development except in very special circumstances.”

It goes on: “The scheme would result in emissions to the environment, the impact of which still requires further assessment.”

Under planning laws, the Mayor can choose to reject applications or even appoint himself the local planning authority if he deems them harmful to London’s spatial makeup.

Gordon Ross, a Stop the Incinerator member who ran with the Green Party for a seat in the London Assembly in May, said: “Quite a few of these issues are issues that we’ve raised as an objection – the loss of open land, the reduction in recycling, the air quality issues. There’s so many different issues that this incinerator doesn’t make sense on.”

Shasha Khan, a Green Party activist and secretary of Stop the Incinerator, agreed: “The bulk of our lines of objection appear in the document. There are one or two that are not in there but it’s good that the mayor’s office has picked up on the lines that we were worried and concerned about.

“But I’d go on to say that if you look at the letter it almost reads like a ‘must try harder’ letter, and it’s giving tips on how to actually overcome the hurdles that the Mayor’s office has placed at the head of Viridor.”

The report asks for “further technical information” about the facility’s gas emissions and “a more detailed air quality analysis” before it can be approved.

It also says other sites should be considered for the facility and the developer, Viridor, could make up for the loss of biodiversity by planting trees and installing bird boxes, as well as giving funds to ecological development.

But Ross told EastLondonLines that he would be fundamentally opposed even to a revised plan.

He said: “We’re opposed to incineration. We don’t think that it’s an appropriate way to dispose the waste as the vast majority of waste could be recycled.

“There’s less and less stuff that can’t be recycled – we could have waste reduction, composting, recycling and anaerobic digestion without having to run this multi-billion pound project for the incinerator.”

In a statement from Sutton council, Ransford Stewart, interim executive head of planning and transportation, said: “The Mayor of London has provided a very detailed response to Viridor’s planning application for an Energy Recovery Facility in Beddington. It’s important that everyone has the opportunity to have their say on this important and complex proposal.

“Sutton Council will continue carefully scrutinising the contents of the planning application, seeking expert technical advice where necessary, to ensure there is a sound basis on which to make a planning decision.”

The evidence for the health effects of the incinerator is unclear. The Health Protection Agency, which is investigating urban incineration, says it believes “well run and regulated” plants pose no significant public health risk.

It concluded: “The accumulated evidence on the health risks of incinerators is simply too strong to ignore and their use cannot be justified now that better, cheaper and far less hazardous methods of waste disposal have become available.”